CN102645166B - Rapid low-cost measuring method for fiber length - Google Patents

Abstract

The invention relates to a rapid low-cost measuring method for fiber length, which comprises the following steps of: fiber rod preparation: preparing loose fiber samples to be measured into a fiber rod with fibers which are straightened and are randomly arranged in parallel; tuft preparation: clamping any cross section of the fiber rod, combing floating fibers to obtain a tuft; digital image acquisition: generating a tuft digital image through image acquisition equipment and transmitting the tuft digital image to a computer; tuft curve extraction: extracting the pixel information of the generated tuft digital image and conducting processing and computation to the pixel information to obtain a tuft cure which represents the fiber amount of each cross section of the tuft; and length index calculation: calculating the four length indexes of the fibers according to the tuft curve. The rapid and low-cost measurement of fiber length is realized by adopting the method and the existing universal equipment is utilized to the utmost extent to develop the rapid low-cost measuring method for textile fiber length and matched hardware and software systems.

Description

A kind of fibre length fast and low-cost measuring method

Technical field

The present invention relates to fibre length in field of optical measuring technologies and measure, particularly relate to a kind of fibre length fast and low-cost measuring method, be applicable to length and the distribution character test thereof of the staple fibres such as cotton, kapok, cashmere, wool fibre.

Background technology

Length is an important quality index of textile fibres, and it directly affects yarn strength, filoplume and Fabric Style, be also select spinning equipment, determine technique, the important evidence of product design.The classical way of test fibre length is group weight method, but this method needs operator to possess professional skill, wastes time and energy, and for cotton fiber, the shorter fiber of cashmere equal length, grouping difficulty is very large.

Two large automatization test systems of application are now: HVI and AFIS.This two large test macro can be realized quick, all automatic measurement of fibre length, but also all has some defects.In HVI, sensing equipment can not be measured complete palpus clump, can only, from start measurement from baseline a distance, will ignore some staple fibres like this.AFIS measuring system has fiber and ruptures in shredding, and straightening of fibers, separation and arrangement are all problems, and only have part fiber to be added up at test cell, so test result can exist bias.This two large another important shortcoming of test macro is expensive, and many enterprises and mechanism are difficult to bear.

2003, the people such as Yu Huiyong (number of patent application: 03125118.8) propose fiber to be arranged in from long to short the concordant fibre array diagram in one end, gather after the digital picture of fibre array diagram, it is processed and computational length index.This method is to utilize image treating to replace artificial graphing method to obtain length index from the digital picture of fibre array diagram, but, fibre array is become to one end is neat, the fibre array diagram of even density is very difficult, the operator need to professional skill just can complete, so the method still can not be by penetration and promotion.

2004, Zhu Youdong (number of patent application: 200410061608.1) propose to utilize scanner to obtain fibre image, the brightness value of statistical pixel point obtains curve map (seeing Fig. 1), and this curve is used as must complex curve (being commonly called as photographic apparatus curve).Analysis chart 1 can find that this curve is obviously different from theoretical palpus complex curve, in Fig. 1, curve is convex-shaped in the starting stage (place, peak), its second differential is negative value so, and we derive second differential that proof must complex curve on the occasion of, illustrate that the curve that this method obtains exists larger error.Reason is the surface information that scanner is had to fiber bundle, and after fiber bundle thickness is greater than certain numerical value, brightness of image value no longer increases with fiber bundle thickness is linear, causes the distortion of fiber bundle curve.And in these application documents, do not illustrate how from curve map, to calculate fibre length.

2008, sternly float and utilize camera to take the light-struck fibrous bundle of transmission, obtain digital picture, according to the brightness value of pixel in image, be directly proportional to penetrating light intensity and make the photographic apparatus curve (Donghua University, Master's thesis: the research of cotton fiber colourity and length measurement method and design) of calling oneself.The same year, the people such as the Zhang Zhijie (patent No.: the digital picture that ZL200820157317.6) also proposes to obtain with camera the concordant fibrous bundle in one end converts thereof into the required data of computational length by information transition system, claim adopt transmitted light and reflected light all can, but do not illustrate how to convert image information to data message required in length index computing formula.Though above-mentioned two kinds of easy devices of oneself building are cheap, but because the visual field is larger, no matter be the uniformity coefficient that transmitted light or reflected light are difficult to guarantee incident light source, cannot avoid the irregular direct stack to fiber layer thickness signal of light source, there is the problems such as distortion of camera edge pixel point in next, the degree of accuracy of test and stability are difficult to be guaranteed.

The digital image method that above-mentioned these fibre lengths are measured is not employed so far, it is very poor that its defect is not only signal degree of accuracy, also comprise being obtained the physical significance of curve by digital picture and lacking demonstration with the relation of fiber length distribution, what have only regards acquisition curve as photographic apparatus curve simply, and imitate photographic apparatus curve disposal route and calculate average length, the length calculation method that specifically do not provide having is fuzzy explanation.These all make said method and application demand wide apart.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of fibre length fast and low-cost measuring method, realize length of textile fibre fast, low-cost measurement, maximally utilise existing common apparatus and develop the method for fast measuring of length of textile fibre and hardware, software systems.

The technical solution adopted for the present invention to solve the technical problems is: a kind of fibre length fast and low-cost measuring method is provided, comprises the following steps:

(1) produce converted top: the converted top of staple in bulk sample to be measured being made to straightening of fibers, parallel, random alignment;

(2) produce palpus clump: arbitrary transversal section of gripping fibers bar, comb removes floating fiber, makes palpus clump;

(3) digital image acquisition: generate palpus clump digital picture by image capture device, and imported into computing machine;

(4) palpus complex curve extraction: extract the Pixel Information of the palpus clump digital picture of generation, it is processed and calculate the palpus complex curve of rear each transversal section fibre weight of acquisition sign palpus clump;

(5) length index is calculated: four length index calculating fiber according to palpus complex curve.

In described step (5), 4 length index computing formula are as follows:

Weight average length wherein, l _mfor the length of longest fiber, F (L) is palpus complex curve, and L is palpus clump transversal section coordinate;

Calculate while making k get maximal value, the value of L is modal length l _z, wherein, k is that palpus complex curve is in the curvature at L place;

Quality length $l_p=\frac{2l_{z}F\left(l_z\right)-l_z^2{F}^{\′}\left(l_z\right)+2{\∫}_{l_z}^{l_m}F\left(L\right)\mathrm{dL}}{F\left(l_z\right)-l_z{F}^{\′}\left(l_z\right)};$

Length variation coefficient $\mathrm{CV}(\%)=\frac{\sqrt{D\left(l\right)}}{\stackrel{\‾}{l}}\×100,$ Wherein, $D\left(l\right)={\∫}_0^{l_m}(6L-2\stackrel{\‾}{l})F\left(L\right)\mathrm{dL}.$

Described step (1) comprises following sub-step: take 0.1～1.0g fiber sample to be measured, remove wherein larger impurity, by its garnetting, mix, then by the fiber device of extending, repeatedly extend 1～10 time, make fiber along converted top axially stretch, parallel and random alignment, make a straight bright and clean converted top.

Described step (1) comprises following sub-step: from the strip of semiproduct, pull and get one section of sample, or produce fleece with carding machine combing, then make converted top through the device of extending.

Described step (2) comprises following sub-step: with clamp, clamp at random the arbitrary transversal section of converted top, guarantee that clamping line is axially vertical with converted top, then pull the fiber not being held, and with comb be parallel to clamp mouth by above or below insert converted top, comb removes floating fiber, and first comb palpus clump ending, rear comb root amount to combing 1～10 time; Then with another clamp, be close to former clamp mouth clamping palpus clump, remove initial clamp, and repeat aforesaid operations comb and remove other end floating fiber, make and test with palpus clump.

In described step (3), adopting transmission-type scanning instrument to generate must clump digital picture.

Described step (4) comprises following sub-step: the gray-scale value that extracts each pixel in palpus clump digital picture, respectively each row perpendicular to fiber axis are accumulated to gray-scale value line by line, maximum gradation value after accumulation is decided to be to 1, the maximum fibre weight that represents palpus clump transversal section is 1, this column position is decided to be true origin, and the accumulation gray-scale value of other row and the ratio of maximum gradation value are the relative fibre weight of these row; The relative fibre weight being obtained by gray-scale value conversion is as ordinate, and each row are decided to be horizontal ordinate apart from the actual distance of initial point, and can obtain must complex curve.

Beneficial effect

Owing to having adopted above-mentioned technical scheme, the present invention compared with prior art, there is following advantage and good effect: the classical sample making technology that the present invention detects fiber and in recent years highly developed computing machine, multimedia input equipment combines, and use the basic theories such as random theory and infinitesimal analysis, develop a kind of new fibre length measuring method and hardware and software system, method for making sample used and theoretical research result can be guaranteed to be obtained by image must complex curve and the length distribution of raw sample fiber there is clear and definite quantitative relationship, and then the every length characteristic index of comprehensive accurately calculating, transmission-type scanning instrument used can guarantee to survey the linear relationship of pixel gray-scale value and each transversal section fibre weight of palpus clump.A lot of contradictions between the new ingenious speed that solves existing measuring method of system, accuracy, integrity and cost, degree of convenience, can measure rapidly and accurately fibre length and distribution thereof, and cost are low, and plant maintenance is convenient, are convenient to universal and promote.

Accompanying drawing explanation

Fig. 1 is the curve map that utilizes scanner to obtain in prior art;

Fig. 2 is process flow diagram of the present invention;

Fig. 3 be in the present invention according to digital picture calculate must complex curve figure.

Embodiment

Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment are only not used in and limit the scope of the invention for the present invention is described.In addition should be understood that those skilled in the art can make various changes or modifications the present invention after having read the content of the present invention's instruction, these equivalent form of values fall within the application's appended claims limited range equally.

Embodiments of the present invention relate to a kind of fibre length fast and low-cost measuring method, and the method can quick based on fibre length, low-cost measuring system.This measuring system comprises sample preparation instrument and servicing unit, transmission-type scanning instrument, computing machine and software for calculation.Described sample preparation instrument and servicing unit comprise fiber extend device, clamp and comb.Described transmission-type scanning instrument, working method is transmission-type, and attribute is anti-phase, and for scanning palpus clump to obtain the gray level image of palpus clump, picture format is bmp, and is transferred to computing machine by interface.Described computing machine for receive must clump digital picture, and provide running environment for software for calculation.Described software for calculation is self-editing program that can independent operating.As shown in Figure 2, the method comprises the following steps:

(1) produce converted top: the converted top of staple in bulk sample to be measured being made to straightening of fibers, parallel, random alignment.

Take 0.1～1.0g fiber sample to be measured, remove wherein larger impurity, by its garnetting, mix, then by the fiber device of extending, repeatedly extend 1～10 time, make fiber along converted top axially stretch, parallel and random alignment, make a straight bright and clean converted top.Also can from the strips such as the sliver of semiproduct, wool top, pull and get one section of sample, or produce fleece with Small Sized Carding Machines combing, then make converted top through the device of extending.The described fiber device of extending is the preparation device of cotton fiber length grouping test use.

(2) produce palpus clump: according to the converted top obtaining, make palpus clump, palpus clump refer to the fiber samples being scanned when length testing.

With clamp, clamp at random the arbitrary transversal section of converted top, guarantee that clamping line is axially vertical with converted top, then pull the fiber not being held, and with comb be parallel to clamp mouth by above or below insert converted top, comb removes floating fiber, and first comb palpus clump ending, rear comb root amount to combing 1～10 time.Then with another clamp, be close to former clamp mouth and clamp palpus clump, remove initial clamp, and repeat aforesaid operations comb and remove other end floating fiber, make the heavily approximately palpus clump for Dual-Ended Loop Test of 10～50mg of wide about 5cm.The one large advantage of this method for making sample is: clamp clamps after converted top, and the converted top that respectively it is stretched out to the clamping line left and right sides carries out combing, can make the two ends palpus clump for testing simultaneously, can improve easily sample size and representativeness.

(3) digital image acquisition: generate palpus clump digital picture by image capture device, and imported into computing machine.Wherein, digital image acquisition apparatus is transmission-type scanning instrument, and the uniformity coefficient that so can guarantee incident light source is that each point light transmission capacity and fiber layer thickness are proportional, and can avoid reflective scanning mode instrument mainly to reflect must clump surface information and the test error that brings.

(4) palpus complex curve extraction: extract the Pixel Information of the palpus clump digital picture generating, after it is processed and is calculated, each transversal section fibre weight of acquisition sign palpus clump must complex curve.

Extract the gray-scale value of each pixel in palpus clump digital picture, respectively each row perpendicular to fiber axis are accumulated to gray-scale value line by line, maximum gradation value after accumulation is decided to be to 1, the maximum fibre weight that represents palpus clump transversal section is 1, this column position is decided to be true origin, and the accumulation gray-scale value of other row and the ratio of maximum gradation value are the relative fibre weight of these row.The relative fibre weight being obtained by gray-scale value conversion is as ordinate, and each row are decided to be horizontal ordinate apart from the actual distance of initial point, can obtain palpus complex curve F (L), sees Fig. 3.

(5) length index is calculated: four length index calculating fiber according to palpus complex curve.

Must depend on sampling method with the relation of raw sample length distribution by clump.Converted top comb folder sampling method according to the present invention is known: the bite of fiber is random along fibre length direction, and the probability that fiber is held is directly proportional to its length and radical frequency, and long is l (0 < l≤l _m, l _mlength for longest fiber) fiber at any point by the probability of gripping is:

k·l·p(l)

Wherein k is constant, and equaling must clump and the number of fiber ratio of raw sample, and p (l) is raw sample length radical frequency density function.

The total radical of fiber that represents raw sample with N, N _lrepresenting long in palpus clump is the number of fiber of l:

N _l＝N·k·l·p(l)

So fibre length radical frequency density function f (l) is in palpus clump:

$f\left(l\right)=\frac{N\&CenterDot;k\&CenterDot;l\&CenterDot;p\left(l\right)}{{\&Integral;}_0^{l_m}N\&CenterDot;k\&CenterDot;l\&CenterDot;p\left(l\right)\mathrm{dl}{}^{}}=\frac{\mathrm{lp}\left(l\right)}{{\&Integral;}_0^{l_m}\mathrm{lp}\left(l\right)\mathrm{dl}}---\left(a\right)$

Raw sample number of fiber average length with following formula, calculate:

$\stackrel{\&OverBar;}{l}={\&Integral;}_0^{l_m}\mathrm{lp}\left(l\right)---\left(b\right)$

(b) formula (a) formula of bringing into is obtained:

$f\left(l\right)=\frac{l}{\stackrel{\&OverBar;}{l}}p\left(l\right)---\left(c\right)$

Due to fibre length weight distribution p _w(l) with the pass of length radical distribution be:

$p_w\left(l\right)=\frac{l}{\stackrel{\&OverBar;}{l}}p\left(l\right)---\left(d\right)$

(c), (d) formula simultaneous are obtained:

f(l)＝p _w(l) (e)

Visible, the length radical of the palpus clump being made by converted top comb gripping quadrat method distributes and equals the length weight distribution of raw sample.

Must refer in clump, to stretch out a certain distance L (0≤L≤l of clamping line by complex curve equation _m, l _mlength for longest fiber) relative fibre weight F (L) and the relation of L.

For arbitrary long be the fiber of l, if l < L can not produce contribution to F (L).While only having the length of stretching out clamping line when l >=L and its to be not less than L, this fiber could have contribution to F (L), and L is stochastic variable.It is that the probability that bite drops on L right side is that this fiber stretches out probability that clamping line length is not less than L:

$\frac{l-L}{l}$

The probability that in palpus clump, this fiber exists is f (l), and therefore, the fiber that in palpus clump, length is l → l+dl to the contribution of F (L) is:

$f\left(l\right)\frac{l-L}{l}\mathrm{dl}$

Therefore the relative total amount F of fiber (L) being held at L place must complex curve theoretical equation be:

$F\left(L\right)={\&Integral;}_L^{l_m}\frac{l-L}{l}f\left(l\right)\mathrm{dl}---\left(f\right)$

To sum up, bring (e) formula into (f) Shi Ke get:

$F\left(L\right)={\&Integral;}_L^{l_m}\frac{l-L}{l}{p}_w\left(l\right)\mathrm{dl}---\left(g\right)$

(g) the palpus complex curve theoretical equation of the new method of testing that formula is proposition, it distributes directly related with the weight frequency density of raw sample.

To (g) formula, ask a subdifferential to obtain:

$F^{\&prime;}\left(L\right)=-{\&Integral;}_L^{l_m}\frac{p_w\left(l\right)}{l}\mathrm{dl}---\left(h\right)$

Ask second differential to obtain:

$F^{\&prime;\&prime;}\left(L\right)={\left[F^{\&prime;}\left(L\right)\right]}^{\&prime;}=\frac{p_w\left(L\right)}{L}---\left(i\right)$

The pass that abbreviation (i) formula obtains palpus complex curve and testing sample fibre weight frequency density function is:

p _w(L)＝LF″(L) (1)

Wherein: L is for stretching out a certain distance L of clamping line in clump; p _w(L) be the fibre length weight frequency density function of raw sample.

1. weight average length

According to the definition of expectation, can obtain:

$E\left(l\right)={\&Integral;}_0^{l_m}l{p}_w\left(l\right)\mathrm{dl}---\left(2\right)$

Wherein: l is fibre length.

(1) formula is brought into (2) formula and carried out integration by parts and can obtain weight average length computing formula be:

$\stackrel{\&OverBar;}{l}=2{\&Integral;}_0^{l_m}F\left(L\right)\mathrm{dL}$

Wherein: l _mfor longest fiber length.

2. modal length l _z

According to can be derived from by complex curve:

$k_{l_0}\&Proportional;p_w\left(l_0\right)$

Wherein: F (l ₀) be a bit on palpus complex curve, l ₀for horizontal ordinate; for l ₀locate bent curvature of a curve; p _w(l ₀) for length be l ₀the weight frequency density of fiber.The abscissa value that can obtain thus the point of maximum curvature on palpus complex curve is exactly the modal length of raw sample, length while making k get maximal value is modal length l _z.

3. quality length

According to the definition of quality length, can obtain:

$l_p=\frac{{\&Integral;}_{l_z}^{l_m}l{p}_w\left(l\right)\mathrm{dl}}{{\&Integral;}_{l_z}^{l_m}{p}_w\left(l\right)\mathrm{dl}}---\left(3\right)$

After bringing (1) formula into (3) formula abbreviation, must quality length computation formula be:

$l_p=\frac{2l_{z}F\left(l_z\right)-l_z^2{F}^{\&prime;}\left(l_z\right)+2{\&Integral;}_{l_z}^{l_m}F\left(L\right)\mathrm{dL}}{F\left(l_z\right)-l_z{F}^{\&prime;}\left(l_z\right)};$

4. the coefficient of variation

By variance, define and can be able to lower equation:

$D\left(l\right)={\&Integral;}_a^{l_m}{(l-\stackrel{\&OverBar;}{l})}^2{p}_w\left(l\right)\mathrm{dl}---\left(4\right)$

Wherein a is the length of staple fibre

Bringing (1) formula into (4) formula abbreviation obtains:

$D\left(l\right)={\&Integral;}_0^{l_m}(6L-2\stackrel{\&OverBar;}{l})F\left(L\right)\mathrm{dL}$

Therefore can obtain the coefficient of variation is: $\mathrm{CV}(\%)=\frac{\sqrt{D\left(l\right)}}{\stackrel{\&OverBar;}{l}}\&times;100.$

With three specific embodiments, further illustrate the present invention below.

Embodiment 1

(1) get 300mg bombax cotton, remove wherein larger impurity, by its garnetting, mix, then by the fiber device of extending, extend 5 times, make fiber along converted top axially stretch, parallel and random alignment, make one mix, straight bright and clean converted top.

(2) with clamp, clamp at random the arbitrary transversal section of converted top, make to clamp line axially vertical with converted top, pull the fiber not being held, and with special-purpose comb parallel clamp jaws by above or below insert converted top, comb removes floating fiber, then with another clamp, is close to former clamp mouth clamping palpus clump, removes initial clamp, and repeat aforesaid operations comb and remove other end floating fiber, make the palpus clump for Dual-Ended Loop Test of the heavily about 30mg of wide about 5cm.

(3) digital image acquisition: by must being laid on the glass tray of professional scanner by clump of making, clamping line is perpendicular to the X-axis of scanner.Scan type is made as: GTG; Resolution: 1000dpi; Scanned medium: positive; Attribute: anti-phase; Brightness, shadow, contrast, color correction are all 0.Then image is carried out to preview, carries out prescan after choosing desired zone, generate 256 grades of gray-scale maps, finally by Image Saving in computing machine, form is bmp.2339 pixels of figure image width, high 2307 pixels.

(4) must complex curve extract: as calculated in digital gray-scale map each col width be: 0.0254mm, utilize software for calculation to extract the gray-scale value of each pixel, just calculate the gray-scale value of accumulation line by line of each row, maximal value is decided to be to 1, by the row location zero point at its place, calculate other row and obtain with its ratio the relative quantity that each is listed as, using it as ordinate, each is listed as from the actual distance at zero point and is decided to be horizontal ordinate, and obtaining thus must complex curve (referring to Fig. 3).

(5) length index is calculated: utilize software for calculation according to length computation formula and obtain must complex curve calculate fibre length index and be: average length: 18.09mm; Modal length: 18.29mm; Quality length: 19.48mm; The coefficient of variation: 17.60%.

Embodiment 2

(1) from semiproduct, choose one section of sliver, with clamp, clamp at random the arbitrary transversal section of sliver, make to clamp line axially vertical with converted top, pull the fiber not being held, and with special-purpose comb parallel clamp jaws by above or below insert converted top, comb removes floating fiber, then with another clamp, be close to former clamp mouth clamping palpus clump, remove initial clamp, and repeat aforesaid operations comb and remove other end floating fiber, make the palpus clump for Dual-Ended Loop Test of the heavily about 0.05g of wide about 5.5cm.

(2) digital image acquisition: by must being laid on the glass tray of professional film scanner by clump of making, clamping line is perpendicular to the X-axis of scanner.Scan type is made as: GTG; Resolution: 2000dpi; Scanned medium: positive; Attribute: anti-phase; Brightness, shadow, contrast, color correction are all 0.Then image is carried out to preview, carries out prescan after choosing desired zone, generate 256 grades of gray-scale maps, finally by Image Saving in computing machine, form is bmp.6480 pixels of figure image width, high 4780 pixels.

(3) must complex curve extract: as calculated in digital gray-scale map each col width be: 0.0127mm, utilize software for calculation to extract the gray-scale value of each pixel, calculate the gray-scale value of accumulation line by line of each row, maximal value is decided to be to 1, by the row location zero point at its place, calculate other row and obtain with its ratio the relative quantity that each is listed as, using it as ordinate, each is listed as from the distance at zero point and is decided to be horizontal ordinate, and obtaining thus must complex curve.

(4) length index is calculated: utilize software for calculation according to length computation formula and obtain must complex curve calculate fibre length index and be: average length: 26.62mm; Modal length: 27.18mm; Quality length: 28.41mm; The coefficient of variation: 20.53%.

Embodiment 3

(1) through Small Sized Carding Machines combing, produce polyster fibre net, therefrom get 0.50g fiber, with the fiber device of extending, extend 3 times, make fiber along converted top axially stretch, parallel and random alignment, make one mix, straight bright and clean converted top.

(2) with clamp, clamp at random the arbitrary transversal section of converted top, make to clamp line axially vertical with converted top, pull the fiber not being held, and with special-purpose comb parallel clamp jaws by above or below insert converted top, comb removes floating fiber, then with another clamp, is close to former clamp mouth clamping palpus clump, removes initial clamp, and repeat aforesaid operations comb and remove other end floating fiber, make the palpus clump for Dual-Ended Loop Test of the heavily about 0.04g of wide about 5.5cm.

(3) digital image acquisition: by must being laid on the glass tray of professional film scanner by clump of making, clamping line is perpendicular to the X-axis of scanner.Scan type is made as: GTG; Resolution: 1000dpi; Scanned medium: positive; Attribute: anti-phase; Brightness, shadow, contrast, color correction are all 0.Then image is carried out to preview, carries out prescan after choosing desired zone, generate 256 grades of gray-scale maps, finally by Image Saving in computing machine, form is bmp.3077 pixels of figure image width, high 1878 pixels.

(4) must complex curve extract: as calculated in digital gray-scale map each col width be: 0.0254mm, utilize software for calculation to extract the gray-scale value of each pixel, calculate the gray-scale value of accumulation line by line of each row, maximal value is decided to be to 1, by the row location zero point at its place, calculate other row and obtain with its ratio the relative quantity that each is listed as, using it as ordinate, each is listed as from the distance at zero point and is decided to be horizontal ordinate, and obtaining thus must complex curve.

(5) length index is calculated: utilize software for calculation according to length computation formula and obtain must complex curve calculate fibre length index and be: average length: 34.85mm; Modal length: 35.31mm; Quality length: 35.86mm; The coefficient of variation: 2.2%.

Claims (7)

1. a fibre length fast and low-cost measuring method, is characterized in that, comprises the following steps:

(1) produce converted top: the converted top of staple in bulk sample to be measured being made to straightening of fibers, parallel, random alignment;

(2) produce palpus clump: arbitrary transversal section of gripping fibers bar, the converted top that respectively it is stretched out to the clamping line left and right sides carries out combing, and comb removes floating fiber, makes Dual-Ended Loop Test and uses palpus clump;

(3) digital image acquisition: generate palpus clump digital picture by image capture device, and imported into computing machine;

(4) palpus complex curve extracts: the Pixel Information of extraction palpus clump digital picture, it is processed and calculates the palpus complex curve that rear acquisition characterizes each transversal section fibre weight of palpus clump;

(5) length index is calculated: four length index calculating fiber according to palpus complex curve.

2. fibre length fast and low-cost measuring method according to claim 1, is characterized in that, in described step (5), 4 length index computing formula are as follows:

Weight average length , wherein, l _mfor the length of longest fiber, F (L) is must be from curve, and L is fibre length;

Calculate , the length while making k get maximal value is modal length l _z, wherein, k must exist by complex curve

The curvature at L place;

Quality length $l_p=\frac{{2l}_{z}F\left(l_z\right)-l_z^2{F}^{\&prime;}\left(l_z\right)+2{\&Integral;}_{l_z}^{l_m}F\left(L\right)\mathrm{dL}}{F\left(l_z\right)-l_z{F}^{\&prime;}\left(l_z\right)};$

Length variation coefficient $\mathrm{CV}(\%)=\frac{\sqrt{D\left(l\right)}}{\stackrel{\&OverBar;}{l}}\&times;100$ , wherein, $D\left(l\right)={\&Integral;}_0^{l_m}(6L-2\stackrel{\&OverBar;}{l})F\left(L\right)\mathrm{dL}.$

3. fibre length fast and low-cost measuring method according to claim 1, it is characterized in that, described step (1) comprises following sub-step: take 0.1～1.0g fiber sample to be measured, remove wherein larger impurity, by its garnetting, mix, then by the fiber device of extending, repeatedly extend 1～10 time, make fiber along converted top axially stretch, parallel and random alignment, make a straight bright and clean converted top.

4. fibre length fast and low-cost measuring method according to claim 1, it is characterized in that, described step (1) comprises following sub-step: from the strip of semiproduct, pull and get one section of sample, or produce fleece with carding machine combing, then make converted top through the device of extending.

5. fibre length fast and low-cost measuring method according to claim 1, it is characterized in that, described step (2) comprises following sub-step: with clamp, clamp at random the arbitrary xsect of converted top, guarantee that clamping line is axially vertical with converted top, then pull the fiber not being held, and with comb be parallel to clamp mouth by above or below insert converted top, comb removes floating fiber, first comb must from ending, comb root amount to combing 1-10 time; Then with another clamp, be close to former clamp mouth and clamp palpus clump, remove initial clamp, and repeat aforesaid operations comb and remove other end floating fiber, make palpus clump for Dual-Ended Loop Test.

6. fibre length fast and low-cost measuring method according to claim 1, is characterized in that, in described step (3), adopting transmission-type scanning instrument to generate must clump digital picture.

7. fibre length fast and low-cost measuring method according to claim 1, it is characterized in that, described step (4) comprises following sub-step: the gray-scale value that extracts each pixel in palpus clump digital picture, respectively each row perpendicular to fiber axis are accumulated to gray-scale value line by line, maximum gradation value after accumulation is decided to be to 1, represent must clump transversal section maximum fibre weight be 1, this column position is decided to be true origin, the accumulation gray-scale value of other row and the ratio of maximum gradation value are the relative fibre weight of these row; The relative fibre weight being obtained by gray-scale value conversion is as ordinate, and each row are decided to be horizontal ordinate apart from the actual distance of initial point, and can obtain must complex curve.